Archaelogical... Jesus.
Not much on that, unless you want to talk about how they could of been wrong about Sparta's 'no trade' idea, and talk about all the Lacadomonian artefacts found in other parts of Greece - Pottery (Backup about the fact that there was a kiln found in a Spartan village), as well as some ivory and bone
Also on ivory, had to of come from Africa, or maybe Asia Minor... Sure as hell the Spartans didn't go down there and conquer for it... They traded for it
Also Spartan settlements in modern-day Italy, go back on how one of the Lycurgan reforms was that Spartiates weren't allowed to leave.
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Thats all I got for now, if I can think of some more, i'll post